502MPI alarm
 

I have had a nagging alarm that nobody can figure out, the motor is a 2000 502mpi, the ecu was reprogrammed by Tyler (approx 75 hrs ago). I only threw that in because apparently 502's dont have a knock sensor alarm and I guess it was added. The code that we are getting is either #44 or #45 (cant remember), it says "electronic spark advance not detected". This does not happen every time I take the boat out, just every so often, usually after rougher water run.

The knock sensor is new, we Ohm'd the connection between the sensor and the ecu and we ran the boat with a scan tool and the timing is advancing. The boat runs great, just worried because this is a new motor and the alarm was going off on the old motor too. Injectors were sent out and cleaned, I have also be running 89 and 93 octane latelty .

Do you think that code means a bad connection?

Does the ecu constantly monitor for the knock sensor or does it only send a signal when it experiences a knock?

Any thoughts?

I am not blaming him, the boat ran the whole 06 season without the problem, it started this year. Maybe I do need to send the ecu out to get reprogrammed though.

If your motor is a 2000 it has a knock sensor. I'd guess that the connector for the knock sensor is broken.
I'm pretty sure that it monitors constantly. I really don't know for sure. I'm still learning this stuff.

Alarm should only go off for high water temp, low oil pressure and low drive lube. Just a constant beep every 3-4 seconds. You should be able to disconnect the alarm sensors one at a time and find out which is setting it off.
My 2000 502mpi started doing it last week too. I already eliminated the lube sensor as the cause.

the fault code that is stored indicates that it is the knock sensor, but everything checks out fine. The alarm is a single beep every 15-30 seconds, not constant.

Assuming your talking about a code 44, the information I have says;

Code 44 - No knock detected

Set after 513 TDC knock free events, RPM > 3000 and MAP >70 and filtered sensor noise < 0.14 volts

Possible causes; Disconnected sensor, broken/open circuit, faulty knock sensor

As far as the alarm, the MEFI3 ECM's can be programmed to alarm any time a fault is set. Some of the earlier Mercrsuier MEFI3's had the fault alarm turned on from the factory (see Service Bulletin 99-3)

Dave